1. Field of the Invention
The present invention relates to a power conversion apparatus which includes a high-power factor converter for converting an alternating current (AC) voltage into a direct current (DC) voltage and an insulated DC/DC converter provided in a subsequent stage thereof.
2. Description of the Related Art
A conventional power conversion apparatus includes an AC/DC converter section for controlling a power factor of a commercial AC power supply to perform AC/DC conversion and a DC/DC converter section which is provided in a subsequent stage of the AC/DC converter section and insulated by a transformer (see, for example, Japanese Patent Application Laid-open No. 2008-118727).
For example, in the conventional power conversion apparatus described above, in order to charge a DC power supply 1 and a DC power supply 2 which are insulated from each other, a primary-side switching circuit of the DC/DC converter section is switched while an ON duty of a semiconductor switching element is fixed or variable. In this case, the duty is determined based on which of the DC power supply 1 and the DC power supply 2 is preferentially charged, but is not determined in accordance with an output voltage and current. Therefore, when a primary-side ON duty of the DC/DC converter section is to be fixed, it is necessary to provide an additional switching means (bidirectional switching means in Japanese Patent Application Laid-open No. 2008-118727) on a secondary side. However, there is a problem that control is complicated and a loss of the DC/DC converter section increases.